The difference between the use of soft and hard ball valve seal

Ball valve seal is the use of soft and hard are different, mainly structural, valve manufacturing standards vary. Ball valve cover pneumatic valve, electric ball valve, flange ball valve. Structural Mechanism The ball valve's hard seal is a metal-to-metal seal that seals both the ball and seat. Processing accuracy and technology more difficult, generally used in high pressure, usually 35MPa above. Soft seal is a seal between metal and non-metallic, such as nylon \ tetrafluoroethylene, the standard is the same. Sealing material on the soft and hard seal is the sealing material of the valve seat, the hard seal is precision machined seat material to ensure that with the spool (ball) with the precision, generally stainless steel and copper. Soft seal refers to the sealing material embedded in the valve seat is non-metallic material, because the soft sealing material has a certain elasticity, so the relative precision of the machining requirements will be low. Manufacturing process due to a lot of chemical industry, machinery industry, the working environment is more complex, many are high temperature and pressure, medium friction resistance, strong corrosive, and now the technology advances, the use of various materials is better, the processing and so on Can keep up with the hard-sealed ball valves are widely promoted. In fact, the principle of hard seal ball valve and soft seal is the same, but because of the seal between the metal, taking into account the relationship between the hardness of the metal, and conditions, what medium to go. Generally require hardening treatment, the ball and valve seat to be constantly grinding to seal. Hard seal ball valve production cycle is long, complex processing, hard seal ball valve is not easy to do. Conditions of use of soft seal can be achieved generally high seal, and hard seal is required on the basis of high and low; soft seal requires fire, because the high temperature, the soft seal material leakage, and hard seal is not the problem ; Hard seal can generally do very high pressure, soft seal will not work; soft seal due to the flow of media problems, some occasions can not be used (such as some corrosive media); Finally, the hard seal valve is generally more expensive than the soft seal . As for the manufacturing, the difference is not large, mainly the difference between the seat, soft seal is non-metallic, hard-sealed metal. Selection of equipment in the above soft and hard seal ball valve selection based mainly on process media, temperature and pressure, the general medium containing solid particles or wear or temperature is higher than 200 degrees the best selection of hard-sealed, large diameter of more than 50 large valve pressure also Open the valve to consider the size of torque, torque should be used when a large fixed hard seal ball valve, regardless of the seal level of soft and hard seals can reach 6.